1. Field of Invention
The present invention relates to an air filter, and more particularly to a filter device which is adapted to block pollutant from polluted air coming from a wide variety of sources, such as from a combustion engine of a transportation vehicle, or from cooking.
2. Description of Related Arts
Air filters have been utilized in a wide variety of areas. The main purpose is to block undesirable pollutants from a mixture of air and those pollutants so that users in the environment in which the filters are used are able to breath with reasonably clean and safe air. As a matter of conventional art, most air filters present some sorts of discrepancies. Some may have the problem of unsatisfactory performance, while others may have the problem of inconvenient application.
As an illustration, polluted air coming out from combustion engine may be considered. Since the invention of combustion engine, an associated phenomenon of air pollution has become one of the most pressing problems around the world. In the past, when the vast majority of people were too poor to own a private vehicle, air pollution was generally tolerable. Nowadays, private vehicles have become necessity for everybody. The development of society is such that virtually everyone can afford to secure some sorts of vehicles (whether they be luxury class, economy class or second hand) for his/her own use. The pollution problem will become intolerable if the nation wants to maintain sustainable development of society.
As a matter of fact, there exist handfuls of techniques which aim to reduce air pollution problem in associated with combustion engines. For example, sulphur content of fuels has generally been reduced to the level which does not produce significant pollution problem. Moreover, most combustion engines have been redesigned in their geometric structures to mitigate the problem of incomplete combustion for minimizing pollutant formation.
However, increasing use of vehicles in recent years means that the reduction of pollutant in individual combustion engines is always compensated by the increase in combustion engine utilization, even to the extent that the various measures taken to combat air pollution have virtually no effect at all. Therefore, further development to reduce air pollution is inevitably required.
As a matter of fact, apart from targeting on fuels and performance of combustion engines, some sorts of filtering devices have been developed and installed to exhaust pipes of vehicles for filtering air pollutant before the combustion air is ultimately discharged into the atmosphere. Although achieving some success, those filtering devices have a significant drawback of affecting the overall performance of the vehicles in question.
A conventional air filter usually comprises at least one, usually two to four, filtering layer forming a plurality of meshes or grips for blocking pollutant from the air passing through the air filter. In such circumstances, air particles are allowed to pass though the filtering layer while larger particles are trapped or stopped by the meshes or grids. As a result, the air passing through the air filter is filtered and should be free of unwanted particles. In practice however, conventional air filter has a significant limitation that where the particles are smaller than the meshes or the grids, they can still pass through the air filter and remain in the air. Very often, carbon particles as well as respiratory particulates are so small that conventional meshes or grids simply allow them to go without filtering.
Of course, one way of resolving this problem is to increase the density of the meshes or grids on the filtering layers such that smaller particles can be blocked as well. Though technically possible, this kind of air filters is usually manufactured by sophisticated technology so that their ultimate selling price is totally unsuitable or unrealistic for widespread applications.
Coming back to domestic environment, the problem enshrined in, for example, domestic range hood is that contaminated air is usually discharged to atmosphere without significant filtering. This causes significant pollution problem for neighborhood. At the same time however, it is difficult to block oil contaminant by incorporating some sorts of oil filters in a conventional range hood.